Are there some papers or specifications intensity and coverage on some materials? There should exist a optimum intensity and coverage for a given metallic materials.
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yukuigao
[reposted by Jack-original posted as poll]
MIL-S-13165 now an SAE spec AMS-S-13165 gives a table for suggestions of shot peening intensity for various materials of various thickness
Mr. Champaigne
I have two questions?
1. If the MIL-S-13165 is now SAE spec AMS-S-13165
But our customer drawings still show their drawings to be MIL-S-13165 is this still ok to use?
2. We are having problems qualifying our machine with our current parameters (.008-.010 intensity). Nothing has changed as far as material specs and shot. We have always qualified our machine with the parameters that have been used for the past 20yrs. I know that the flow meter does not work and I have stressed to the maintenance department to have this flow meter fixed. The machine parameters have been changed to get the machine to qualify. Do you have any suggestions?
Parameters Changed: Orifice plate was 3/16 opened up to 3/8
Lance setting was backed away by 1.25”
Pressure was 50psi +-5 changed to 80psi
12 IPM changed to 6 IMP
Your help is greatly appreciated.
1. The decision to continue using MIL-S-13165 or AMS-S-13165 is a policy issue. Some organizations require continued usage of a updated, or cancelled, specification while others may require migration to the newer version. Be aware that AMS-S-13165 has been cancelled with re-direct to AMS 2430. You should ask your customer for specific instructions on which spec he expects you to comply to.
2. Increasing your orifice plate to 3/8" will increase the shot flow rate (substantially). This increase in shot flow rate will reduce the air pressure at the nozzle (not at the source) thus your intensity will drop unless you increase the air pressure, as you have done, from 50 psi up to 80 psi. I'm not clear why you would have changed your travel speed from 12 to 6 in/minute. This would affect coverage rate and since you are already throwing almost twice as much media per minute you shouldn't have had to change your travel speed.
Are you preparing complete saturation curves (four or more strips exposed at increaseing exposure times, or in your case decreasing inch/minute feedrate)? Are you really sure the media is within requirements (size, hardness, shape). What grade of Almen strips are you using?
We use T1 and T2 to set the intensity and saturation curve. The strips being used are A 1
The media is 45-52RC. I think the problem is in the media flow? The machine had an electronic sensor for monitoring media flow. It apparently is not working properly according to our maintenance department, so we cannot monitor the media flow is my guess?
The flow rate is very important! Leaning the shot flow out will help you obtain a higher intensity. I see you opened up your orifice plate, probably not a good idea.
What size shot are you using? Also, using High Hardness Shot 55-62rc would also help.
Shot size is S110 trying to get an intesity of .008-.010.
I would suggest you switch to ASH-170 if possible. .009A is at the high end of what ASH-110 is capable of, and your using ASR-110. Peening with a small shot at the velocity necessary to achieve the intensity you are looking for is potentially damaging to the part surface and you could be doing more harm then good by peening it in this case.
I would also suggest running a complete new saturation curve with a minimum of four points for each intensity verification location. Just running T1 and T2 after making a process change proves nothing.